Franklin’s Gulls nest in freshwater marshes with abundant emergent vegetation and patches of open water. Here, they form large colonies of hundreds or thousands of birds, often nesting less than 2 feet from neighbors. After nesting, Franklin’s wander widely in the intermountain West of North America and in the prairies, where they may be abundant locally, especially where insect prey is emerging in swarms. During migration, Franklin’s Gulls have been detected in almost every corner and habitat of North America, including very high elevations (over 14,000 feet) in the Rocky Mountains. For feeding, they seek out agricultural areas, pastures, and many sorts of wetlands, including sewage ponds, lakes, lagoons, estuaries, and bays. They readily follow tractors during plowing, eating grubs and worms turned up from the soil, and they sometimes visit landfills with other gulls. In South America, Franklin’s Gulls winter mostly along ocean coastlines and forage along shorelines and out to sea about 30 miles, though they also forage at high-elevation lakes in Peru far from the ocean. Like other gulls, Franklin’s are flexible and opportunistic in their foraging and make use of whatever habitats are most productive.Back to top
During the breeding season, Franklin’s Gulls eat mostly invertebrates, especially insects and earthworms, along with small amounts of vegetation, including sunflower seeds, wheat, and oats. Beetles, bugs, grasshoppers, crickets, locusts, flies, midges, dragonflies, and damselflies, plus larval forms of these insects, form the bulk of the diet during the breeding season. Franklin’s Gulls also occasionally consume leeches, snails, crayfish, fish, and small mice. Most of their foraging in spring involves capturing insects in flight over wetlands and farm fields, but they often capture midges by sitting on the water and picking them from the surface as they emerge. In such cases, Franklin’s Gulls spin in circles like phalaropes, bringing prey closer to the water’s surface by creating a vortex beneath themselves. When farming operations are active, they follow tractors, hunting earthworms, grubs, and grasshoppers dislodged by plows and disks. Wintering Franklin’s Gulls eat insects and other invertebrates, along with small fish (anchovy, jack), crabs (especially hermit and mole crabs), and isopods along shorelines. They also take fish scraps from fishing operations and fish-processing factories and associate with other gulls at landfills and refuse dumps.Back to top
Males select display and nest sites in floating vegetation or anchored stems in still, shallow water, near emergent vegetation.
Both male and female build the nest, a platform of wet vegetation, often material stolen from other gulls’ nests, with a central depression. As the nest decays and sinks, adults add new material throughout incubation. Nests begin at about 17 inches across and may grow to 40 inches as material is added. Most have a small ramp on one side.
|Clutch Size:||2-4 eggs|
|Number of Broods:||1 brood|
|Egg Length:||2.0-2.1 in (5.13-5.29 cm)|
|Egg Width:||1.4-1.5 in (3.61-3.73 cm)|
|Incubation Period:||23-26 days|
|Egg Description:||Greenish brown with dark splotches.|
|Condition at Hatching:||Semiprecocial with eyes open. Covered in down. Able to stand within a day, but usually remain in nest for three weeks.|
As soon as Franklin’s Gulls arrive in nesting marshes, they commence courtship, provided snow and ice are gone. Males stand at a display site, usually on floating vegetation, and call to females as they fly overhead. Interested females land near prospective mates, and the males begin to display by turning away and erecting the neck feathers, thus hiding their black heads. Females respond with the same display, and the pair then alternately turn toward and away from each other. Once paired, females solicit food from males by hunching over and raising the head and bill quickly, much like a begging chick. Males regurgitate food in response. This display usually precedes copulation, during which the male calls continually. Franklin’s Gulls are monogamous in their mating system. At the display site, the pair builds a nest together, and both share incubation duties. After egg-laying, both mates also defend the nest area, although in dense colonies they tolerate neighbors without conflict. Both parents feed the chicks, and at least one remains with the young until they fledge. Franklin’s Gulls are highly social during migration, as well as on wintering grounds, and conflict among flock members is limited. When roosting, they associate peaceably with other gull species, terns, and shorebirds in mixed flocks. Franklin’s Gulls are very sensitive to disturbance by predators and humans; they often abandon colonies immediately when disturbed. “Panic flights” occur at the first sign of trouble: large numbers of these usually noisy gulls rise up off their nest sites and fly over the colony area in complete silence for several minutes.Back to top
According to the North American Breeding Bird Survey, Franklin's Gull populations declined throughout the species’ range by almost 3% per year between 1968 and 2015, resulting in a cumulative decline of 76% over that period. In the United States (which represents only a small portion of the species’ breeding range), declines were over 6% per year during the same period, which amounts to a 95% decline. Partners in Flight estimates a global breeding population of 830,000 and rates the species a 14 out of 20 on the Continental Concern Score, placing it on the Yellow Watch List for species with population declines. Franklin’s Gull populations declined in the 1800s and early 1900s as about half of wetlands in their U.S. range were drained. Other nesting habitats were modified or manipulated to benefit other species (such as waterfowl) and thus became unsuitable for Franklin’s. Their sensitivity to human disturbance at colonies has limited their numbers in some places. Environmental pollutants such as heavy metals also pose a threat to this aquatic species. Climate change forecasts of warmer temperatures throughout the breeding range, with both stronger storms and intense periods of drought, could reduce nesting habitat and nesting success.Back to top
Burger, Joanna and Michael Gochfeld. (2009). Franklin's Gull (Leucophaeus pipixcan), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
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